Hydraulic system for operation of motors



April 21, 1953 w. c. HODGES ET AL 2,635,430

HYDRAULIC SYSTEM FOR OPERATION OF MOTORS Original Filed Oct. 31, 1949 6 Sheets-Sheet l William C. Hodges Alexander L. Robb.

ATTORNEYS April 21, 1953 w. c. HODGES ETAL 2,635,430

HYDRAULIC SYSTEM FOR OPERATION OF MOTORS Original Filed Oct. 31, 1949 6 Sheets-Sheet 2 0 E d 148 152 HRS 152 15s *JQQ 1419 INVENTORS ATTORNEYS April 21, 1953 w. c. HODGES ETAL 2,635,430

HYDRAULIC SYSTEM FOR OPERATION OF MOTORS Original Filed Oct. 31, 1949 6 Sheets-Sheet 3 INVENTORS F WLLLiam C. Hodgi s A lexarnder L. Robb.

BY Mai W fl I 7371/ ATTORNEYS April 1953 w. c. HODGES ETAL 2,635,430

HYDRAULIC SYSTEM FOR OPERATION OF MOTORS Original Filed Oct. 31, 1949 6 Sheets-Sheet 4 INVENTORS Will/Lam C. Hodgfies AIeacanderL.Robb.

cmmflQ w ATTORNEYS April 1953 w. c. HODGES ET AL 2,635,430

HYDRAULIC SYSTEM FOR OPERATION OF MOTORS Original Filed Oct; 51, 1949 6 Sheets-Sheet 5 ("q a WtI/l C. Hodges AlxanderL. Robb.

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ORNEYS April 21, 1953 w. c. HODGES ET AL HYDRAULIC SYSTEM FOR OPERATION OF MOTORS 6 Sheets-Sheet 6 Original Filed Oct. 31, 1949 w T N E V m U a WLLLiam C. Hodgies AI/exanderL. Robb.

@mmMd/m/ fl ATTORNEYS Patented Apr. 21, 1953 UNITED STATES PATENT OFFICE HYDRAULIC SYSTEM F MOTORS R OPERATION OF Original application October 31, 1949, Serial No. 124,592. Divided and this application August 29, 1951, Serial No. 244,191

Claims.

This invention relates to hydraulic systems for handling transportable containers and more particularly to such systems by which less than carload lot sized containers are transferred from and to various types of transporting means or transferred from or to loading docks and the like from or to various types of transporting means.

Heretofore many systems and devices have been proposed for shifting less than carload lot sized containers between various means of transportation or to or from loading docks and the like from or to various transporting means. These known systems and devices are subject to various objections, including unnecessarily complicated and expensive apparatus for efiecting the transfer of the containers and for these reasons such systems and apparatus have not been accepted commercially. These known systems and apparatus require such massive and cumbersome machinery for effecting the transfer of the container that the transporting equipment with which such mechanism is associated is thereafter unsuited for any use but the transportation of specially designed less than carload lot containers and these containers can be handled only with such equipment and cannot be utilized as separate mobile units.

By the present invention we have overcome all of the inherent difliculties in these known systems and have further provided a novel system for the transfer of less than carload lot containers which is of such a simple yet powerful construction that the apparatus does not in any way preclude the use of the transporting equipment for other purposes than the transportation of the less than carload lot sized containers used with our invention.

We have overcome the difliculties inherent in known systems by providing the less than carload lot containers with power actuated reciprocal casters at each corner of the container so that the container may be readily raised by extension of the casters into position for rolling on the same or readily lowered from such raised position so that the container will rest on its bottom and the casters may be retracted above the bottom of the container. In conjunction with the casters we have provided power means running on tracks set into the bed of the container transporting means and preferably powered from the engine of the transporting means to move the container upon its casters onto and off of the transporting means. When the container is to be moved from one transporting means to another or from the transporting means to a loading dock or the ljkg w gmploy bridging elements to bridge the space between the transporting means or the transporting means and the loading dock over differences of elevation thereof to provide a track for the casters and to support the container in transfer. Our system is so constructed and arranged that it is possible for one man to effect and control the transfer of containers of large size without danger either to the operator or to the container and its contents. By providing the container with castering support at each corner it is possible to readily move the container from one position to another. The container may be readily towed or pushed into any desired position thus making it possible to effect load transportation from point of origin to point of ultimate disposition without shifting of the load from the container.

It is accordingly an object of the present invention to provide a novel hydraulic system for efiecting the transfer of less than carload lot containers.

Another object is to provide such a system in which hydraulically powered means connected into the system are mounted upon tracks in the bed of the transporting means are employed for moving the container onto or off of the transporting means.

Another object is to provide such a system in which the container may be hydraulically raised and lowered onto and off of supporting casters to facilitate transfer of the same and to provide a completely mobile container for use as individual units.

Another object is to provide such a system in which the power for effecting the transfer of the container is preferably obtained from the driving power of the container transporting means although such power may be obtained from any other suitable source.

Another object is to provide such a system which is relatively simple and inexpensive to install on existing types of transporting means and which may be used by unskilled personnel with minimum training and experience.

Another object is to provide novel hydraulic systems for raising and lowering the casters arranged at each corner of the container.

Another object is to provide a novel system for utilizing the power of the transporting means to power the power means employed for moving the container.

Another object is to provide such a novel system which can be readily installed on known types of transporting means without major modification thereof and without so changing the stood therefore that this illustrative embodi ment of our invention in no way defines or limits the same and reference should be had to the appended claims for this purpose:

This application is a division of application Serial No. 124,592, filed October 31, 1949.

Referring now to the several drawings, inwhich like reference characters indicate like parts,

Fig. 1 is a somewhat schematic representation of a truck equipped with our system for transferring a transportable van or container'to a railroad flatcar at higher elevation than the bed of the truck and showing the several elements of the present invention in'position for commencing such a transfer;

Fig. 2 is another view of the illustrative embodiment of Fig. 1 showing the van partially transferred onto the railroad flatcar;

Fig. 3 is a side view of a portion ofthe transferable container to illustrate in detail the structure of the mechanism for raising and lowering the casters;

Fig. 4 is an end view of the section of the container shown in Fig. 3* to further illustrate the mechanism employed for raising and lowering the casters;

Fig. 5 is a schematic showing of the hydraulic system of our invention showing the hydraulic system incorporated with the truck'and the hydraulic system of the transferable container, both systems being connected to apply hydraulic power to the casters to raise them above the level of the bottom of the container;

Fig. 6 is a further showing of the systems of Fig. 5 in which the systems are connected to apply hydraulic power to the casters to raise the container and place its weight upon the several casters;

Fig. '7 is a schematic representation of the hydraulic system of the truck connected to the power transfer means for actuating these means in parallel during the transfer of the container; and

Fig. 8 is a schematic representation ofv the hydraulic system of the truck connected to the power transfer means for actuating these means in series during transfer of the container.

Referring now to the several figures, and more particularly to Figs. 1 and 2, it is there seen that in this illustrative embodiment, a hydraulic system is provided for transferring a transportable container generally indicated at 50, to or from a truck or other suitable transporting means generally indicated at 5|, transfer being effected either to or from any other suitable type of transporting means here shown as a conventional railroad fiatcar generally indicated at 52. The transferable container 50- is mounted upon castering wheels 53, one at each corner thereof, and these wheels during transfer cross bridging elements 54, bridging the space between the truck and the fiatcar. Transferable containers 50 are moved upon casters 53 in transfer by means of one or more suitable hydraulically powered transfer means 55 which are coupled thereto by coupling 56. Power transfer means 55 are mounted upon rails let transversely into the bed of the truck 5| and flush therewith. These rails are provided with extensions 58-.

As noted above, the system of this illustrative embodiment of our invention for raising and lowering the transferable container 50 and for energizing the power transfer mechanisms 55 is hydraulic and this hydraulic power is applied to power transfer means 55 through hoses generally indicated in these figures at 59 and 80. It should be noted that this system is so constructed and arranged that the entire transfer of container 50 may be effected by the driver of the truck without assistance and without employing any. other systemthan that described herein.

Assume that container 55 is resting upon its bottom on truck 5! and that it is desired to transfer the same from truck 5| to fiatcar 52. The driverof truck 5| brings the same into proximity with fiatcar 52 and as nearly parallel thereto as practical. It should be understood that it is not essential to the operation of our invention that truck 5| be parallel to flatcar 52 and at the same elevation as fiatcar 52 since bridging elements 54 can compensate for differences both in parallelism and in elevation, and power transfer means 55 are powerful enough to overcome differences in elevation above or below the truck level of at least 12' inches with container 50 fully loaded. Having brought the truck 5| into proximity with fiatcar 52, the driver then places rail extensions 58in position on the side of the truck away from fiatcar 52 to provide continuations of the rails beyond the side of the truck. Power transfer mechanisms 55 are then mounted upon rail extensions 58 and connections 56 are secured to the side of container 50 away from the fiatcar 52. The hydraulic system of the present invention is then energized to raise casters 53 above the floor level of the container, as will more fully appear hereinafter, so that bridging rails 54 may be placed in position under the casters adjacent to fiatcar 52 to bridge the space between flatcar 52 and truck 5|. The hydraulic system is then energized to lower the casters 53' to raise the container off of its bottom and to place the weight thereof upon the several casters 53.

The hydraulic system is then connected to the power transfer mechanisms 55, hoses 59 and 60 being shown for this purpose. Hydraulic power is then supplied, to mechanisms 55 and energizes the same and drives them along rail extensions 58, pushing container 50 towards flatcar 52. This movement is continued until power mechanisms 55 complete the transfer of the container from the truck to the flatcar in a smooth and continuous movement, the casters riding over bridging elements 54.

When container 5|! has been positioned upon the flatcar 52, the hydraulic system is suitably adjusted to raise the casters 53 to lower the container upon its bottom on the flatcar. The transfer is now completed and the driver of the truck then disconnects the couplings 55 from the container and reverses the motion of mechanisms 55 to bring them back onto rail extensions 58, whereupon he disconnects hoses 59 and 60 from them, and removes the mechanisms from the rail extensions and places them in any suitable compartment provided on the truck chassis. Rail extensions 58 are removed and bridging elements 54 are also removed and placed in a suitable carrying compartment or rack upon the truck. The truck is then ready to be used for any other purpose or to pick up another transferable container.

When the transfer is to be efiected from the fiatcar to the trailer, and the transferable container 50 is upon the flatcar 52, the truck 5| is positioned adjacent to flatcar 52 and rail extensions 58 are placed in position. Power mechanisms 55 are then mounted on extensions 58 and hoses 59 and 6|! are connected. Hydraulic power is then applied to mechanisms 55 to move them across the bed of trailer 5| and couplings 53 are secured to the side of the container. The casters 53 of container 50 are raised, if necessary, to allow bridging elements 54 to be put into position to bridge the space between trailer 5| and flatcar 52. Hydraulic power is then applied to the casters 53 of container 50 to raise container 58 ofi of its bottom so that the weight of the container is supported upon the casters 53. Hydraulic power is then applied to transfer mechanisms 55 to roll container 55 upon its casters 53 off of the flatcar 52 and across the bridging elements 54 onto trailer 5|. As soon as container 50 has moved completely onto truck 5|, the hydraulic system is actuated to stop transfer mechanisms 55 and then to retract casters 53 so that container 50 rests upon its bottom on truck 5|. The several elements are then disconnected as above described, and placed in suitable containers carried by truck 5| and truck 5| is then ready to drive away with the container, it being obvious, that suitable means may be employed to secure the container 50 to the truck 5|, or for that matter, to flatcar 52 and that these ties must be secured or broken as the case may be at the beginning and end of each transfer.

Figs. 3 and 4 show in detail the structure employed for raising and lowering the casters 53. This mechanism comprises a cylinder I38 in which is mounted a double-acting piston, not shown, provided with a piston rod I39. Cylinder I33 is secured to container 59 by any suitable means here shown as by bracket I40 which is suitably secured to the container as by bolts I4I. Ears I42 may also be suitably secured to container 55 to receive the upper end of cylinder I38, pin I43 being provided to secure the same. Hoses I54 and I45 connecting into the hydraulic system of the container, as will be described hereinafter in more detail, provide hydraulic fluid to cylinder I33 to move the piston therein. Brackets I46 and I4? are secured to container 50 by any suitable means as by bolts I48 and a cylindrical caster leg I49 is mounted for reciprocation therein. Leg I49 is pivotally connected to piston rod I39 at I50. A spline I5I is secured to leg I49 and is mounted in a suitable slot let into bracket I47 to prevent rotation of leg I49 during reciprocation. Caster 53 is mounted in the lower end of leg I49.

Brackets I40, I46 and I41 are provided with pivots I52 upon which hinges I53 are mounted. Hinges I53 are suitably secured to doors I54 of container 55. Since brackets I45, I45 and I41 are mounted at the corners of container 55, this hinge structure permits doors I54 to open the width of the container 5|] and to rotate into open-position in contact with the sides of the container, thus providing a large area of ingress or egress for the container.

Figs. 5 and 6 show schematically the hydraulic system incorporated with the transferable container 55. As noted above, this hydraulic system is designed to raise and lower the casters 53.

This. system may obtain hydraulic fluid under pressure, either from lines connected thereto from a source of hydraulic pressure driven by the truck motor, an independent source of power, or the container hydraulic system may be operated by a hand pump integral therewith. Heretofore the cylinders for actuating casters 53 have been designated by numeral I38. In the description of this hydraulic system, it will be necessary to identify each cylinder in turn and accordingly in these figures one cylinder is designated by this number and the other three cylinders are indicated by numerals 2II, 2I2 and 2I3. The lower sides of cylinders I38 and 2H are cross manifolded by line 2I4. Line 2|4 is connected by line 2 5 with a cross manifolding line 2I6 connecting the lower sides of cylinders 2|2 and 2|3. Line 2|! connects line 2I6 with one side of a suitable manually operable pump 2I8. The upper sides of cylinders 2I2 and 2I3 are cross manifolded by line 2|9 for reasons which appear more fully hereinafter, which is connected to a suitable manually operable valve 220. A line 22| leads from the upper end of cylinder 2|I to a suitable manually operable valve 222. Line 223 leads from the upper end of cylinder I38 to a third suitable manually operable valve 224. One outlet of each of valves 22!], 222 and 224 are connected by line 225 to a line 226 which extends across the container and is provided at its ends with suitable quick disconnecting valves 227 and 228 which close automatically upon uncoupling. A second line 229 extends across the container and terminates at each end in valves 239 and 23I which are similar to valves 221 and 228 and connects into line 2I5. The third side of each of valves 223, 222 and 224 are connected by line 232 to the intake side of pump 2I8. A suitable accumulator 233 is connected between line 232 and line 2|! with a check and relief valve 234 interposed adjacent line 2I'I. This relief valve 234 is set at a pressure exceeding the return pressure drop to reservoir 244. Accumulator 233 is preloaded to a pressure sufficient to balance a volume of fluid stored therein against valve 234 equivalent to the maximum differential volume of the cylinders. This differential volume will always be stored in accumulator 233. A suitable valve 235 is positioned in line 2I'I adjacent pump H8 and has a connection 236 with line 226 and a connection 23'! with line 232.

In the operation of the hydraulic system of the container, as above described, the pressure for actuating the several pistons may be provided by the hand pump 2|8. It is anticipated that the more usual procedure will be to employ the hydraulic system incorporated with the truck or a suitable independent source to provide hydraulic fluid under pressure to actuate the several pistons to raise and lower the casters. A suitable hydraulic system for the truck is shown in Fig. 5 connected to the hydraulic system for the container with both systems arranged to raise the pistons in the cylinders on the container at the beginning of the trans fer operation to permit the bridging rails to be inserted beneath the casters. In this figure a conventional internal combustion engine transmission is shown at 238 with a conventional power take off 240 driving a conventional pump 24I. Pump MI is provided with an outlet or pressure line 242 and areturn line 243. A conventional reservoir for hydraulic fluid is connectedto line 243 and is shown at 244. A bypass from supply line 242 back to reservoir 244 is shown at 245 and is provided with a. pressure relief valve 246 so that when the pressure in supply line 242 exceeds a predetermined value, valve 246 will open and by-pass the hydraulic fluid under pressure back to reservoir 244. Supply line 242 terminates in a quick connect coupling of any suitable type 241. A return line 248 is connected to reservoir 244 and terminates in any suitable quick connect coupling 249. This hydraulic system may be incorporated with the tractor of a conventional tractor-trailer type of truck.

The hydraulic system about to be described may be incorporated with the trailer of the tractor-trailer type or truck noted above. The trailer is provided with a hydraulic fluid supply line 250 which is connected at 241 to the system of the tractor and is provided with a return line 25! which is connected at 249 to the return line 248 of the tractor system. Lines 250 and 25! both terminate at 252 and 253, respectively, in quick connect couplings so that other hydraulic systems may be connected to this system when desired, as when a tandem trailer rig is being used. Line 250 is connected by line 254 with reverse control valve 255. Line 256 connects valve 255 to line 25!. Line 251 connects valve 255 to a second valve 258 and to flexible hose 259 which terminates in any suitable quick connect coupling 250. Line 26! connects valve 255 with a suitable flexible hose 262 which terminates in any suitable quick connect coupling 263. Valve 258 is connected by line 264 with any suitable flexible hose 265 which terminates in a quick connect coupling 266. Line 261 connects valve 258 to valve 268 and valve 268 is connected by a line 269 with flexible hose 210 which terminates in quick connect coupling 21!. Valve 268 is connected by line 212 with line 26!.

When it is desired to supply hydraulic fluid under pressure to the hydraulic system of the container from the hydraulic system of the tractor and trailer couplings 268 and 21! are connected respectively to couplings 23! and 228 and valves 255, 258 and 268 are positioned as shown. Power take oif 248 then actuates pump 24! which supplies hydraulic fluid under pressure to line 242 and through connection 241 to lines 259 and 254 to valve 255. From valve 255 the hydraulic fluid under pressure enters line 259 and through couplings 260 and 23! enters line 229 of the hydraulic system of the container. After the hydraulic fluid has been utilized in the hydraulic system of the container it is returned to line 226 of the container system and through couplings 228 and 21! to the hose 219 and line 269 to valve 268. From valve 268 the return fluid passes into line 26! and through valve 255 into line 256, thence into line 25! and through coupling 249 into the return line 248 of the tractor system and through reservoir 244 and line 243 to the return side of pump 24!. Surplus hydraulic fluid stored in accumulator 233 will be discharged through the hydraulic system to the reservoir 244.

When it is desired to raise the casters of the container utilizing the hydraulic power supplied by the tractor-trailer hydraulic system valve 235 is closed and valves 220, 222 and 224 are positioned as shown in Fig. 5. The hydraulic fluid under pressure enters line 229 and passes to the underside of the pistons in the several cylinders through lines 2|5, H4, and M6. This raises the pistons in the several cylinders and thus raises the several casters. Hydraulic fluid above the pistons in the several cylinders passes into the return line 226 of the container system and thence to the pump, as described above. The fluid above the pistons in cylinders H2 and 2 !3 passes into line 2!!) and thence through valve 220 into line 225 and into return line 226. The liquid above the pistons of cylinders 2!! and I 38 passes into lines 22! and 223 respectively and thence through valves 222 and 224 respectively into line 225 and into return line 226.

When it is desired to elevate the container so that its weight rests entirely upon the casters and to utilize the hydraulic system afforded by the tractor and trailer, the container hydraulic system and the tractor and trailer hydraulic systems are disposed as shown in Fig. 6. In this arrangement the tractor and trailer hydraulic systems are adjusted as above described so that hydraulic fluid under pressure leaving valve 255 enters line 26! and thence through line 212 to valve 268 and to line 269 into flexible hose 210. Since hose 210 is connected through couplings 21! and 228 with line 226 of the container hydraulic system line 226 becomes the pressure line. Fluid under pressure from line 226 passes into line 225 and through valve 224 into line 223 and into cylinder I38 above the piston therein. Hydraulic fluid under pressure in line 225 also passes through valve 222 and line 22! into cylinder 2 I above the piston therein. Line 225 also supplies hydraulic fluid under pressure through valve 220 to line 2!!! which passes the hydraulic fluid into cylinders 2| 2 and 2l3 above the pistons therein. Hydraulic fluid under pressure above the pistons of the several cylinders depresses the same and raises the container upon the several casters. The hydraulic fluid beneath the pistons in the several cylinders passes into the return line, now line 229. The fluid beneath the piston in cylinder 2! 3 passes upward in line 2|6 into line H5 and thence into line 229. The hydraulic fluid beneath the piston in cylinder 2!2 passes through line 2l5 into line 229. The fluid beneath the piston in cylinder I38 passes through line 2! 4 into line H5 and thence into line 229. The fluid beneath the piston in cylinder 2!! passes directly into line U5 and thence into line 229. Return liquid in line 229 passes through couplings 23! and 269 into line 259 and thence through valve 255 into line 25! and is returned to pump 24! through coupling 249, line 248, reservoir 244 and line 243. Surplus oil in accumulator 233 will pass to reservoir 244 as described above.

When the container is raised upon its casters quick connect couplings 268 and 21! may be broken so that the hydraulic system of the tractor-trailer may be employed to drive the power mechanisms 55. In providing hydraulic fluid to the power mechanisms '55 for energizing the same it is desirable in some instances to connect the power mechanisms 55 in series for uniform movement and in other cases it is desirable to connect the power mechanisms 55 in parallel for independent control and slower operation. The hydraulic system of the tractor and trailer may be utilized for this purpose. Fig. 7 shows the same arranged to connect the power mechanisms 55 in parallel. The hydraulic system schematically shown in Fig. 8 discloses the arrangement of the hydraulic system of the tractor and trailer adjusted to connect the power mechanisms 55 in series.

Referring now to Fig. 7 it is there seen that fluid under pressure from pump 24! will pass through line 242 and coupling 241 into line 250 and thence through line 254 and through valve 255 into hose 2-59 and into one power mechanism 55. Hydraulic fluid is discharged from this power mechanism 55 through hose 2'!!! into line 269 and thence through valve 268 and line 212 into line 26! and line 256 for return to line 25!, to line 248, reservoir 245 and pump 24!. The hydraulic fluid under pressure passing through valve 255 also passes into line 25'! and thence through valve 258 into line 265 and into the other of the power mechanisms 55. The hydraulic fluid discharged from the second power mechanism 55 passes into line 252 and into line 25! and thence through valve 255 into line 25!, line 248, and reservoir 244 to the return side of pump 24!. Thus it will be seen that the power mechanisms 55 are connected in parallel.

If it is desired to reverse the direction of movement of power mechanisms 55 when connected in parallel, as in Fig. '7, valve 255 is reversed without changing the position of valves 258 and 258. The hydraulic fluid under pressure in line 254 is then directed into what was the return line system as above described while what was previously the pressure line system, as above described, becomes the return line system. By reversing valve 255 fluid under pressure is admitted to line 25! and thence through flexible hose 262 to one of the power mechanisms 55. Fluid under pressure is also admitted to line 212 and thence through valve 268 into line 269 and into the other power mechanism 55. Fluid discharged from the first of the power mechanisms 55 passes through line 265 and through valve 258 into line 25'! and through valve 255 into line 255 for return to the pump 24!. Fluid discharged from the other of the power mechanisms 55 passes through flexible conduit 259 and through valve 255 into line 256 for return through line 25! to pump 24!. Thus the hydraulic system provided by the tractor and trailer permits rapid and easy reversal of movement of the power mechanisms 5'5 by merely shifting the position of valve 255. It is therefore obvious that the direction of movement of the container can be easily adjusted during transfer and power mechanisms 55 can be indefinitely controlled by adjustment of valves 258 and 265.

When it is desired to connect the power mechanisms 55 so that each such power mechanism 55 obtains the full volume of hydraulic fluid from pump 24!, it is necessary to connect the same in series and the adjustment of the hydraulic system of the tractor and trailer to provide this series connection is shown in Fig. 8. In this arrangement fluid under pressure passes from pump 24! through line 242 and coupling 24'! into line 250 and thence into line 254 and valve 255. From valve 255 hydraulic fluid under pressure passes into hose 259 and thence into the first of the power mechanisms 55. Discharge fluid from the first power mechanism 55 passes through hose 210 and line 269 directly through valves 268 and 258 into hose 265 and thence into the second of the power mechanisms 55. The discharge from the second power mechanism '55 passes through hose 262 into line 26! and thence through valve 255 into line 256 and into line 25! for return to the pump 24!, as described above.

Reversal of the direction of motion of the power mechanisms 55 is obtained by merely reversing the position of valve 255. When valve 255 is reversed fluid under pressure from line 254 enters line 26! and passes through hose 262 into the first of the power mechanisms 5'5. The fluid discharged from the first of the power mechanisms 55 passes outward through hose 265 and directly through valves 258 and 268 into line 269 and hose 2'!!! and into the second of the power mechanisms 55. The discharge from the second power mechanism 55 passes through hose 259 into valve 255 and from valve 2'55 into line 256 for return to the pump 24! through lines 25! and 248. This hydraulic system thus provides a ready means for accurately and promptly controlling the direction of motion of the power mechanisms 55 when connected in series and thus provides a simple and direct control for the motion of the container in transfer.

It is now-apparent that by the present invention we have provided a novel hydraulic system for transferring less than carload lot containers from one means of transportation to another or to or from one means of transportation to or from a dock or the like, which system efliciently accomplishes all of the objectives described above.

It will now be apparent to those skilled in the art that changes in or modifications to the above described illustrative embodiment of our invention may now be made without departing from our inventive concept. For example the several valves of the hydraulic system may be any of the valves known to the art suitable for this purpose and having the appropriate number of valve ports. In some instances it may be necessary to modify or adjust such known valves to adapt them for our purposes or to provide such valves with bleed lines or other connections to make them operate as desired which is all within the skill of one skilled in this art. The hydraulic system may also be modified to eliminate the use of the accumulator by providing non-diiierential pistons and cylinders for the casters. It is also Within the scope of our invention to modify the hydraulic system to combine the several valves into a single valve, if desired, or to provide suitable controls for the several valves so that they may be controlled by the operator as described by single means. Reference should therefore be had to the appended claims to determine the scope of this invention.

What is claimed is:

1. In a hydraulic system for supplying hydraulic fluid under pressure in series or in parallel to a plurality of hydraulically actuated means, a source of hydraulic fluid under pressure, means for connecting the pressure side of said source to a four-way valve, means for connecting a second side of said valve to one of said hydraulically actuated means, means for connecting one of said hydraulically actuated means to one side of a three-way valve, means for connecting the second side of said four-way valve to a second three-Way valve, means for connecting the second side of said second three-way valve to a second of said hydraulically actuated means, means for connecting said second hydraulically actuated means to the second side of said first named three-way valve and to the third side of said four-way valve, means for connecting the third sides of said three-way valves and means for connecting the fourth side of said four-way valve to the return side of said source of hydraulic fluid under pressure.

2. In a hydraulic system for supplying hydraulic fluid under pressure in series or in parallel to a plurality of hydraulically actuated motors and for selectively supplying hydraulic fluid under pressure to a system for actuating pistons, a source of hydraulic fluid under pressure, pressure and return lines for said source, means for connecting said motors across said lines, valve means in said connecting means for controlling the flow of hydraulic fluid to said motors individually,

valve means for controlling the direction of flow of hydraulic fluid through said connecting means, means for disconnecting one of said motors from said connecting means and for connecting said connecting means to a second pair of lines for hydraulic fluid, a plurality of cylinders, pistons in said cylinders, means for connecting one of said second pair of lines to said cylinders beneath said pistons, means for connecting the other of said second pair of lines to said cylinders above said pistons, and valve means in said last named connecting means for selectively connecting said cylinders above said pistons to the other of said second pair of lines. v

3. A hydraulic system as described in claim 2 including manually actuated means for supplying hydraulic fluid connected across said second pair of lines and valve means for controlling the direction of flow of hydraulic fluid through said second pair of lines and for disconnecting said manual means from said second pair of lines.

12 v 4. A hydraulic system as described in claim 2 including an accumulator connected across said second pair of lines and a check and relief valve in the connection to said accumulator.

5. A hydraulic system as described in claim 2 having four of said cylinders in which said last named valve means includes a separate manually actuated valve for an adjacent pair of said cylinders and a single manually actuated valve for the other pair of said cylinders.

WILLIAM C. HODGES. ALEXANDER L. ROBB.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,060,220 Kennedy Nov. 10, 1936 2,112,466 Maloon Mar. 29, 1938 2,304,418 McMurry Dec. 8, 1942 2,575,507 Acton Nov. 20, 1951 FOREIGN PATENTS Number Country Date 184,455 Great Britain Oct. 18, 1923 

